JP2012068540A - Camera module and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera module that has a lens suitable for optical correction of hand shake.SOLUTION: A camera module 100 according to the present invention comprises: an optical section 1 having a lens part 11 comprising at least one of optical lenses 11a to 11c, and a lens barrel 12 holding the lens part 11; an image sensor section 5 having a sensor chip 52 for converting light made incident via the lens part 11 into an electrical signal; and an OIS section 3 for correcting the displacement of an optical axis relative to the sensor chip 52 by shifting the relative positions of the optical section 1 and the image sensor section 5 in a direction parallel to the imaging surface of the sensor chip 52 according to the inclination of an apparatus body. The curve of image height to optical distortion of the lens part 11 has the positive maximum value in an intermediate image height area and gradually decreases from the maximum value toward the maximum image height.

Description

  The present invention relates to a camera module, and more particularly to a camera module including a lens shift type or sensor shift type optical camera shake correction mechanism.

  2. Description of the Related Art Conventionally, image pickup apparatuses such as digital video cameras and digital still cameras have been put into practical use having an optical image stabilization mechanism (Optical Image Stabilizer, hereinafter referred to as OIS) that corrects blurring of captured images due to camera shake. .

  The OIS uses a gyro sensor that detects the tilt of the image pickup apparatus due to a camera shake operation by an angular velocity or the like. Based on an output signal of the gyro sensor, the image sensor such as a lens or a CCD is moved in a direction perpendicular to the optical axis, that is, an image. The shift of the optical axis with respect to the light receiving part of the image sensor is corrected by shifting in parallel with the light receiving part of the sensor. As a result, the subject image can be relatively stationary, so that blurring of the captured image due to camera shake can be corrected and occurrence of image blurring or the like can be suppressed.

  FIG. 9A is a side view showing an operation at the time of camera shake correction by the conventional camera module 200, and FIG. 9B is a schematic diagram showing a captured image taken by the conventional camera module 200 in FIG. 9A. FIG. As shown in FIG. 9A, when the camera module 200 is tilted with respect to the subject O due to camera shake, the camera module 200 is configured so that the center Oc of the subject O coincides with the optical axis s. 105 is shifted in the -X direction. Accordingly, as shown in FIG. 9B, the blurring of the photographed image due to camera shake is corrected by matching the center OIc of the subject image OI in the photographed image with the center Ic of the photographed image.

  However, as shown in FIG. 9 (b), in the captured image at the time of camera shake correction captured by the conventional camera module 200, the perspective (magnification) of the peripheral portion of the subject image OI changes to cause distortion. was there.

  FIG. 10 is a graph showing the relationship between the image height and the optical distortion when the camera module 200 is tilted with respect to the subject O, as shown in FIG. In FIG. 10, the vertical axis defines the image height (%), and the horizontal axis defines the optical distortion (%). As shown in FIG. 10, when the camera module 200 is tilted with respect to the subject O, the influence of optical distortion increases as the image height indicating the distance from the center position of the captured image increases. If the optical distortion is positive, the subject image at the image height is photographed large, while if the optical distortion is negative, the subject image is photographed small. The optical distortion is a ratio (value) obtained by dividing the difference between the ideal image height and the actual image height by the ideal image height, and there is a difference in optical distortion at the maximum image height (± 100%). Become. As the amount of tilt increases, the distortion of the peripheral portion of the subject image increases.

  FIG. 11 is a graph showing a general image height-optical distortion curve of a lens unit included in the conventional camera module 200 shown in FIG. As shown in FIG. 11, the lens portion provided in the conventional camera module 200 generally has an optical distortion of 0 in the minimum image height (0%) region and a plus in the intermediate image height (± 50%) region. Has a maximum value of. Then, it decreases from the maximum value and has a negative minimum value (± 90%) before the maximum image height (± 100%), and further increases from the minimum value to the maximum image height (± 100%). The image height-optical distortion curve passing through 0 in FIG. That is, it has an optical distortion characteristic in which the optical distortion increases in the vicinity of the maximum image height (± 100%) and the maximum image height.

  FIG. 12 is a graph showing an image height-optical distortion curve of a conventional lens unit during camera shake correction. As shown in FIG. 12, the image height-optical distortion curve of the lens unit at the time of camera shake correction is caused by the shift of the image sensor unit 105 in addition to the change amount of the optical distortion caused by the tilt of the camera module 200 with respect to the subject O. The amount of change in optical distortion is added. Here, in the lens portion having the image height-optical distortion curve shown in FIG. 11, that is, the maximum image height (± 100%) and the optical distortion curve in which the optical distortion increases in the vicinity of the maximum image height, the subject O The amount of change in optical distortion caused by the tilt of the camera module 200 with respect to the angle and the amount of change in optical distortion caused by the shift of the image sensor unit 105 have the same polarity, and the amount of tilt at the time of camera shake correction increases. For this reason, the conventional camera module 200 has a problem in that the perspective (magnification) of the peripheral portion of the subject image OI as shown in FIG.

  With respect to this problem, Patent Document 1 proposes a technique for suppressing distortion of a captured image by performing digital correction by an ISP (Image Signal Processor). According to Patent Document 1, it is possible to suppress distortion of a subject image by recognizing a zoom position and the like, adaptively changing processing parameters, and correcting a captured image stored in a memory.

JP 2006-129175 A (released May 18, 2006)

  However, the technique disclosed in Patent Document 1 requires a high-performance ISP (Image Signal Processor) for executing digital correction. Especially in the case of video shooting, camera shake is always occurring, so a battery that is equipped with a large-capacity buffer memory for high-speed correction and increased power consumption for always driving the circuit Is required.

  For this reason, the technique disclosed in Patent Document 1 has a problem that the configuration becomes complicated and the manufacturing cost increases, and it conflicts with the downsizing of today's imaging apparatus.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to realize a low-cost camera module that is small in size and capable of suppressing distortion of a captured image during camera shake correction.

  In order to solve the above-described problem, a camera module according to the present invention is incident via an optical unit having a lens unit including at least one optical lens and a lens barrel that holds the lens unit, and the lens unit. Sensor means having an image sensor for converting the converted light into an electrical signal, and the relative position of the optical means and the sensor means is shifted in parallel to the imaging surface of the image sensor in accordance with the inclination of the apparatus body. Thus, in a camera module including a camera shake correction unit that corrects a deviation of the optical axis with respect to the imaging element, the image height-optical distortion curve of the lens unit has a positive maximum value in the intermediate image height region, and the maximum It is characterized by a gradual decrease from the maximum value toward the image height.

  Usually, in the image height-optical distortion curve of the lens unit at the time of camera shake correction, in addition to the amount of change in the optical distortion caused by the tilt of the camera module with respect to the subject, the relative position between the optical means and the sensor means by the camera shake correction means is calculated. The amount of change in optical distortion caused by the shift is added. For this reason, the conventional camera module has a problem that the amount of tilt at the time of camera shake correction is increased, and the perspective (magnification) of the peripheral portion of the subject image is greatly changed to cause distortion.

  According to the above invention, the lens unit has an image height-optical distortion curve having a positive maximum value in the intermediate image height region and gradually decreasing from the maximum value toward the maximum image height. . For this reason, at the time of camera shake correction, the amount of change in optical distortion caused by the tilt of the camera module relative to the subject is opposite to the amount of change in optical distortion caused by the relative position shift between the optical means and sensor means by the camera shake correction means. Polarity is canceled out. As a result, the amount of tilt at the time of camera shake correction is reduced as compared with the conventional camera module, so that distortion of the captured image can be suppressed. Note that the above-described reduction in optical distortion includes not only a continuous reduction but also a gradual reduction.

  As described above, according to the above-described invention, it is possible to suppress distortion of a captured image at the time of camera shake correction by optimizing the image height-optical distortion curve of the lens unit. An object of the present invention is to realize a low-cost camera module capable of suppressing distortion of a captured image during correction.

  Further, in the camera module according to the present invention, the image height-optical distortion curve includes an amount of change in optical distortion caused by an inclination of the apparatus body, and a relative position between the optical unit and the sensor unit by the camera shake correction unit. It is preferable that the maximum image height and the reduction amount of the optical distortion in the vicinity of the maximum image height are determined so that the amount of change in the optical distortion caused by the shift of the image becomes approximately the same.

  According to the above invention, the amount of change in the optical distortion caused by the tilt of the camera module with respect to the subject and the optical distortion caused by the relative position shift between the optical means and the sensor means by the camera shake correction means are of the opposite polarity. Will be offset. Note that the range in the vicinity of the maximum image height is appropriately determined based on the tilt of the camera module with respect to the subject and the amount of shift of the relative position between the optical means and the sensor means by the camera shake correction means.

  As a result, the amount of tilt at the time of camera shake correction is further reduced, so that distortion of the captured image can be effectively suppressed.

  In the camera module according to the present invention, it is preferable that the reduction amount is 0.1% or more and 0.5% or less per 1 image height allocation.

  4. The camera module according to claim 2, wherein the intermediate image height region is a region that is not less than 30% and not more than 60% of the maximum image height. 5. .

  According to the above invention, the amount of change in optical distortion caused by the tilt of the camera module with respect to the subject, and the amount of change in optical distortion caused by a relative position shift between the optical means and the sensor means by the camera shake correction means. An image height-optical distortion curve having the same reverse polarity can be preferably obtained.

  In the camera module according to the present invention, it is preferable that the camera shake correction unit is a lens shift type optical camera shake correction mechanism that corrects a deviation of an optical axis with respect to the imaging device by shifting the optical unit. .

  In the camera module according to the present invention, it is preferable that the camera shake correction unit is a sensor shift type optical camera shake correction mechanism that corrects a deviation of an optical axis with respect to the image pickup device by shifting the sensor unit. .

  According to the above invention, the camera shake correction means is constituted by the lens shift type or sensor shift type optical camera shake correction mechanism.

  Accordingly, it is possible to suppress distortion of a captured image at the time of correction by a lens shift type or sensor shift type optical camera shake correction mechanism.

  In order to solve the above problems, an imaging apparatus according to the present invention includes the camera module.

  Thereby, it is possible to realize a small imaging device that can suppress distortion of a captured image during camera shake correction at a low cost.

  As described above, the camera module according to the present invention includes a lens unit including at least one optical lens and an optical unit having a lens barrel that holds the lens unit, and light incident through the lens unit. By shifting the relative position of the optical means and the sensor means in parallel with the imaging surface of the imaging element according to the inclination of the apparatus body, and the sensor means having the imaging element for converting into an electrical signal, In the camera module including a camera shake correction unit that corrects a deviation of the optical axis with respect to the imaging element, the image height-optical distortion curve of the lens unit has a positive maximum value in the intermediate image height region, and has a maximum image height. On the other hand, it gradually decreases from the maximum value.

  For this reason, it is possible to suppress the distortion of the captured image at the time of camera shake correction by optimizing the image height-optical distortion curve of the lens unit without providing a special ISP (Image Signal Processor) as in the prior art.

  Therefore, according to the above-described invention, there is an effect that it is possible to realize a camera module that is small in size and can suppress distortion of a captured image at the time of camera shake correction.

It is a perspective view which shows the external appearance structure of the camera module which concerns on this invention. It is AA sectional drawing of the camera module shown by FIG. 1, and has shown the state which cut | disconnected the center part of the camera module in the optical axis direction. It is a graph which shows the image height-optical distortion curve of the lens part shown by FIG. It is a perspective view which shows schematic structure of the OIS part shown by FIG. FIG. 5A is a side view showing a state in which the camera module faces the subject, and FIG. 5B is a schematic diagram showing a photographed image taken by the camera module in FIG. is there. 6A is a side view showing a state in which the camera module is tilted with respect to the subject, and FIG. 6B is a schematic diagram showing a photographed image taken by the mellar module in FIG. 6A. . FIG. 7A is a side view showing an operation at the time of camera shake correction by the camera module, and FIG. 7B is a schematic diagram showing a captured image taken in FIG. 7A. It is a graph which shows the optical distortion of the lens part at the time of camera shake correction | amendment shown by Fig.7 (a). FIG. 9A is a side view showing an operation at the time of camera shake correction by a conventional camera module, and FIG. 9B is a schematic diagram showing a photographed image taken by the conventional camera module in FIG. 9A. is there. FIG. 9A is a graph showing the relationship between the image height and the optical distortion when the camera module is tilted with respect to the subject as shown in FIG. It is a graph which shows the general image height-optical distortion curve of the lens part with which the conventional camera module shown by Fig.9 (a) is provided. It is a graph which shows the image height-optical distortion curve of the conventional lens part at the time of camera shake correction.

  An embodiment of a camera module according to the present invention will be described below with reference to FIGS. In the present embodiment, a camera module provided with a sensor shift type optical image stabilization mechanism (OIS: Optical Image Stabilizer) will be described. In the following description, various technically preferable limitations for carrying out the present invention are given, but the scope of the present invention is not limited to the following embodiments and the accompanying drawings.

[1] Configuration of Camera Module The configuration of the camera module according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing an external configuration of a camera module 100 according to the present embodiment. As shown in FIG. 1, the camera module 100 includes an optical unit 1 that is an imaging optical system, a lens driving unit 2 that drives the optical unit (optical unit) 1, and an OIS unit (camera shake correction unit) that performs camera shake correction. 3 and an imaging unit 4 that performs photoelectric conversion of light incident from the optical unit 1.

  The optical unit 1 is held inside the lens driving unit 2, and the imaging unit 4 includes an image sensor unit 5 and a substrate 6 on which the image sensor unit 5 is mounted. That is, the camera module 100 has a configuration in which an image sensor unit (sensor means) 5, an OIS unit 3, and a lens driving unit 2 are stacked in this order on the substrate 6 in the optical axis direction. For convenience, the optical unit 1 side is referred to as the upper side, and the imaging unit 4 side is referred to as the lower side.

  FIG. 2 is a cross-sectional view taken along the line AA of the camera module 100 shown in FIG. 1, and shows a state where the central portion of the camera module 100 is cut in the optical axis direction.

  The optical unit 1 is an imaging optical system that forms a subject image. The optical unit 1 collects light from a subject incident from the outside and guides it to the image sensor unit 5 of the imaging unit 4. As shown in FIG. 2, the optical unit 1 includes a lens unit 11 and a lens barrel 12 that holds a side surface of the lens unit 11.

  The lens unit 11 collects light from the subject and forms an image on the light receiving unit of the sensor chip 52 included in the image sensor unit 5. In the present embodiment, the lens unit 11 includes three optical lenses 11a to 11c. The lens unit 11 may be composed of a single optical lens, but by forming the lens unit 11 with a plurality of optical lenses 11a to 11c as in the present embodiment, various imaging can be performed. In the present embodiment, the image height-optical distortion (distortion aberration) curve of the lens unit is optimized in order to suppress distortion of the captured image during camera shake correction, which will be described later. Details of the image height-optical distortion curve of the lens unit 11 will be described later.

  The lens barrel 12 is a circular cylindrical member, and the lens portion 11 is held on its inner peripheral surface so that the optical axis of the lens portion 11 coincides with the axial center of the lens barrel 12. The lens barrel 12 is held by the lens holder 21 by screwing a screw portion formed on the outer peripheral surface thereof and a screw portion formed on the inner peripheral surface of the lens holder 21 included in the lens driving unit 2. Has been.

  The lens driving unit 2 is an autofocus mechanism that adjusts the focal point of the lens unit 11 by moving the optical unit 1 along the optical axis direction. That is, the lens driving unit 2 adjusts the focal point of the lens unit 11 by moving the lens unit 11 upward or downward from the infinity end to the macro end. In this embodiment, the lens driving unit 2 is configured by a VCM type autofocus mechanism, but may be configured by, for example, a piezo actuator or a stepping motor.

  The lens driving unit 2 includes a movable unit that holds the optical unit 1 (lens unit 11) and moves in the optical axis direction when the lens unit 11 is driven, and a fixed unit that does not vary in position. . The movable part is housed inside the fixed part, and includes a lens holder 21 and a coil 22. On the other hand, the fixed portion includes a yoke 23, a permanent magnet 24, a cover 25 and a base 26.

  The lens holder 21 is a circular cylindrical member, and holds the lens barrel 12 with a screw portion formed on the inner peripheral surface thereof. Further, a flange is provided at a lower end portion of the outer peripheral surface of the lens holder 21, and a coil 22 extending in parallel with the outer peripheral surface of the lens holder 21 is fixed to an outer edge portion of the flange.

  Further, springs 27a and 27b are provided at both ends of the lens holder 21 in the optical axis direction. One end of the spring 27 a is fixed to the upper end of the lens holder 21, and the other end is fixed to the yoke 23. On the other hand, the spring 27 b has one end fixed to the lower end facing the upper end of the lens holder 21 to which the spring 27 a is fixed, and the other end fixed to the base 26. The springs 27a and 27b support the lens holder 21 movably in the optical axis direction by its elastic force. The positions where the springs 27a and 29b are fixed are not particularly limited as long as one end is fixed to the movable portion and the other end is fixed to the fixed portion.

  The yoke 23 is a rectangular cylindrical member 23a that is a rectangular cylindrical member constituting the side surface portion of the lens driving unit 2, and a circular cylindrical member that is a circular cylindrical member disposed inside the rectangular cylindrical portion 23a. It is comprised from 23c and the connection part 23b which connects the rectangular cylindrical part 23a and the circular cylindrical member 23c.

  The rectangular cylindrical portion 23 a and the circular cylindrical member 23 c are connected by a connecting portion 23 b at the upper end portion, and the lower end portion of the rectangular cylindrical portion 23 a is fixed to the outer edge portion of the base 26. The yoke 23 is positioned so that the coil 22 is disposed between the rectangular cylindrical portion 23a and the circular cylindrical member 23c, and the inner surface of the rectangular cylindrical portion 23a has a predetermined gap with the coil 22. Thus, the permanent magnet 24 is arranged.

  In the present embodiment, a cover 25 is provided above the connecting portion 23 b, and the cover 25 constitutes an upper surface portion (top surface) of the lens driving unit 2. In addition, an opening 25a for allowing light from the subject to enter is formed in the central portion of the cover 25, and a windshield for preventing entry of foreign substances or the like is provided in the opening 25a. In the present embodiment, the side surface portion of the lens driving unit 2 is constituted by the yoke 23 and the upper surface portion is constituted by the cover 25. For example, the side surface portion and the upper surface portion of the lens driving unit 2 are constituted by the yoke 23. By doing so, the cover 25 may be omitted. In this case, since the yoke 23 also serves as the cover 25, the opening 25 a is formed in the yoke 23.

  The base 26 constitutes the base of the lens driving unit 2, and an opening 26 a is formed at the center of the base 26 in order to secure an optical path.

  As described above, the lens driving unit 2 has a configuration in which the lens holder 21 that holds the lens barrel 12 on the inner peripheral surface is accommodated in the space formed by the yoke 23, the cover 25, and the base 26. In addition, the coil 22, the yoke 23 and the permanent magnet 24 constitute a magnetic circuit, and when a current is applied to the coil 22, an electromagnetic induction phenomenon occurs between the coil 22 and the permanent magnet 24. Due to this electromagnetic induction phenomenon, thrust in the optical axis direction is generated with respect to the lens holder 21 that is integrally fixed to the coil 22. The thrust enables the lens holder 21 to move in the optical axis direction. When the lens holder 21 moves in the optical axis direction, the springs 27a and 27b move while being deformed.

  As shown in FIG. 2, a protrusion 21a is formed at the lower end of the lens holder 21, and when the protrusion 21a is in contact with the base 26, the elastic force of the springs 27a and 27b causes A downward pressure is applied to the lens holder 21.

  Furthermore, in this embodiment, a groove 26b is formed on the upper surface of the base 26 (the surface facing the bottom surface of the lens holder 21) located in the vicinity of the coil 22 and the permanent magnet 24, and the inner surface of the groove 26b is formed on the inner surface of the groove 26b. An adhesive dust trap agent 28 is applied.

  The dust trap agent 28 may be applied to the upper surface of the base 26, but by applying the dust trap agent 28 to the inner surface of the groove 26b as in the present embodiment, foreign matter can be retained in the groove 26b. That is, the foreign matter dropped on the base 26 via the gap between the coil 22 and the permanent magnet 24 can be retained in the groove 26b immediately after dropping. Thereby, since the foreign material which fell on the base 26 can be reliably capture | acquired by the dust trap agent 28, it can suppress effectively that a foreign material is discharged | emitted from the opening part 26a.

  The dust trap agent 28 is not particularly limited as long as it has adhesiveness. For example, a semi-solid (or nearly solid) oil or resin can be used, and grease is particularly preferable. Grease is a kind of fat and oil that is semi-solid or nearly liquid, and can be composed of, for example, a semi-solid (or nearly solid) or paste-like lubricant.

  As the grease, for example, a molybdenum disulfide lubricant, a white lubricant, a silicone lubricant, or a perfluoropolyether lubricant can be used. Or, mineral oil-based grease mainly composed of mineral oil, poly-α-olefin-based grease mainly composed of poly-α-olefin oil, silicone-based grease mainly composed of silicone oil, fluorosilicone-based grease, perfluoropolyether A perfluoropolyether-based grease having a main component can be used. These greases can be used alone or in admixture of two or more. The grease may contain an additive for grease, such as lithium soap, calcium soap, polytetrafluoroethylene (PTFE), and the like.

  The OIS unit 3 is provided on the bottom surface (bottom surface of the base 26) side of the lens driving unit 2, and is a sensor shift type camera shake correction mechanism that performs camera shake correction by shifting the image sensor unit 5 according to camera shake. . Details of the OIS unit 3 will be described later.

  The imaging unit 4 converts the light collected by the optical unit 1 into an electrical signal. The imaging unit 4 includes an image sensor unit 5 and a substrate 6 on which the image sensor unit 5 is placed.

  The image sensor unit 5 includes a glass substrate 51, a sensor chip 52 and a sensor cover 53.

  The glass substrate 51 is made of a translucent member and is disposed so as to cover the light receiving portion of the sensor chip 52. In the present embodiment, an infrared blocking film (IR cut film) is formed on the surface of the glass substrate 51 and has a function of blocking infrared rays.

  The sensor chip 52 is an image sensor that is placed on the substrate 6 and converts the light collected by the optical unit 1 into an electrical signal. That is, the sensor chip 52 is a sensor device that converts an optical signal received through the lens unit 11 into an electrical signal. As the sensor chip 52, for example, a CCD or a CMOS sensor IC can be used. A light receiving unit (not shown) in which a plurality of pixels are arranged in a matrix is formed on the surface (imaging surface) of the sensor chip 52, and the light receiving unit connects the light collected by the optical unit 1. This is a region to be imaged, and can also be called a pixel area.

  The sensor chip 52 converts the subject image formed on the light receiving unit (pixel area) into an electrical signal and outputs it as an analog image signal. The operation of the sensor chip 52 is controlled by a DSP (not shown), and the analog image signal generated by the sensor chip 52 is output to the DSP and processed.

  The sensor cover 53 is provided so as to cover a part of the sensor chip 52 and the surface of the substrate 6, and an opening 53 a is formed to secure an optical path at a position corresponding to the light receiving part of the sensor chip 52. . A step is provided on the inner peripheral surface of the opening 53a, and the glass substrate 51 is supported by the OIS unit 3 and the sensor chip 52 with a predetermined gap by the step. The opening 53 a is a light transmission region that allows light incident through the lens unit 11 to pass through the light receiving unit of the sensor chip 52.

  In this embodiment, the glass substrate 51 is attached to the opening 53a of the sensor cover 53. However, for example, the glass substrate 51 may be bonded and fixed to the sensor chip 52 using an adhesive or the like. However, as in the present embodiment, by arranging the glass substrate 51 with a predetermined gap from the sensor chip 52, the influence of the foreign matter attached to the glass substrate 51, that is, the reflection on the sensor chip 52, is reduced. This is preferable.

  The substrate 6 includes a patterned wiring (not shown), and the image sensor unit 5 (sensor chip 52) and the substrate 6 are electrically connected by the wiring. For the substrate 6, for example, a printed substrate or a ceramic substrate can be used.

  As described above, in the imaging unit 4, the optical signal incident on the sensor chip 52 is converted into an electrical signal, and the converted electrical signal is input to the control circuit or the like (not shown) of the camera module 100 via the substrate 6. Are extracted as image signals.

[2] Image Height-Optical Distortion Curve of Lens Unit Next, an image height-optical distortion curve of the lens unit 11 included in the camera module 100 will be described. FIG. 3 is a graph showing an image height-optical distortion curve of the lens unit 11 shown in FIG. In FIG. 3, the vertical axis defines the image height (%) indicating the distance from the center position of the captured image, and the horizontal axis defines the optical distortion (%).

  As shown in FIG. 3, the image height-optical distortion curve of the lens unit 11 has a maximum value that becomes a positive peak value in the intermediate image height (± 50%) region, and the maximum image height (± 100%). It gradually decreases from the maximum value toward the. That is, the lens unit 11 has an optical distortion characteristic in which the optical distortion gradually decreases in the vicinity of the maximum image height (± 100%) and the maximum image height.

  Since the lens unit 11 has such an optical distortion characteristic, the amount of change in the optical distortion caused by the tilt of the camera module 100 with respect to the subject and the optical distortion caused by the shift of the image sensor unit 5 by the OIS unit 3 during camera shake correction. The amount of change can be reversed (see FIG. 8). The range in the vicinity of the maximum image height is appropriately determined depending on the tilt of the camera module 100 with respect to the subject and the shift amount of the image sensor unit 5 by the OIS unit 3.

  Further, the maximum image height (± 10) is set so that the amount of change in optical distortion caused by the tilt of the camera module 100 with respect to the subject is approximately the same as the amount of change in optical distortion caused by the shift of the image sensor unit 5 by the OIS unit 3. And the amount of decrease in optical distortion in the vicinity of the maximum image height is determined to be 0.1% or more and 0.5% or less per 1 image height allocation. As a result, as will be described later, it is possible to suppress distortion of the captured image at the time of camera shake correction.

  In the image height-optical distortion curve, the positive peak value of optical distortion is located in the region of 30% to 60% of the maximum image height (± 100%), and the peak value is 0.5 % Or more and 2.0% or less is preferable. Further, the optical distortion at the maximum image height (± 100%) is preferably −1.0% or more and + 0.1% or less, and the TV distortion is −2.0% or more and −0.5% or less. It is preferable that

  Accordingly, the image height-optical distortion in which the amount of change in optical distortion caused by the tilt of the camera module 100 with respect to the subject and the amount of change in optical distortion caused by the shift of the image sensor unit 5 by the OIS unit 3 have the same reverse polarity. A curve can be suitably obtained.

[3] Configuration of OIS Unit Next, the configuration of the OIS unit 3 will be described with reference to FIG. FIG. 4 is a perspective view showing a schematic configuration of the OIS unit 3 shown in FIG. As shown in FIG. 4, the OIS unit 3 includes an OIS base 31, stepping motors 32 and 33, lead screws 34 and 35, and sub-bases 36 and 37.

  The stepping motor 32 and the lead screw 34 are drive means for driving the sub base 36 in the X-axis direction. The stepping motor 32 is fixed to the OIS base 31 and drives the sub-base 36 fixed to the movable part of the lead screw 34 in the X-axis direction.

  The stepping motor 33 and the lead screw 35 are driving means for driving the sub base 37 in the Y-axis direction. The stepping motor 32 is fixed to the sub base 36, and drives the sub base 37 fixed to the movable part of the lead screw 35 in the Y-axis direction.

  Thereby, the stepping motors 32 and 33 of the OIS unit 3 can be used as a drive source, and the image sensor unit 5 can be shifted in a direction parallel to the X axis and the Y axis.

  The stepping motors 32 and 33 are driven based on an output signal from a gyro sensor (not shown) that detects the tilt of the camera module 100 by acceleration, angular acceleration, angular velocity, and the like, and image according to camera shake. By shifting the sensor unit 5, it is possible to correct the deviation of the optical axis with respect to the light receiving unit of the sensor chip 52.

[4] Operation for Camera Shake Correction Next, an operation for camera shake correction by the camera module 100 will be described with reference to FIGS. FIG. 5A is a side view showing a state in which the camera module 100 is facing the subject O, and FIG. 5B is a photographed image taken by the camera module 100 in FIG. It is a schematic diagram shown.

  In FIG. 5A, O is a rectangular plate-like object, Oc is the center of the object O, 100 is a camera module, 1 is an optical unit, 1c is the center of the optical unit 1, 5 is an image sensor unit, and 5c is an image sensor. The center of the unit 5, S indicates the optical axis of the camera module 100 passing through the center 5 c of the image sensor unit 5 and the center 1 c of the optical unit 1. In FIG. 5B, Ic represents the center of the captured image (frame), OI represents the subject image, and OIc represents the center OIc of the subject image OI.

  As shown in FIG. 5A, when the center Oc of the subject O is on the optical axis s passing through the center 5c of the image sensor unit 5 and the center 1c of the optical unit 1, it is shown in FIG. As described above, the center Ic of the captured image and the center OIc of the subject image OI coincide with each other, and a captured image in which the subject image OI is accurately captured as a rectangle can be obtained.

  6A is a side view showing a state in which the camera module 100 is inclined with respect to the subject O, and FIG. 6B shows a photographed image by the camera module 100 in the state shown in FIG. 6A. It is a schematic diagram. FIG. 6A shows a state in which the camera module 100 is tilted downward in the horizontal direction with respect to the subject O by pressing the shutter button or the like.

  As shown in FIG. 6A, when the optical axis s is shifted downward from the center Oc of the subject O, as shown in FIG. 6B, the center OIc of the subject image OI is also the center of the captured image. It will deviate from Ic. In the case of still image shooting, such a shift between the center OIc of the subject image OI and the center Ic of the shot image occurs at the moment when the shutter is released, causing blur in the shot image. In addition, in the case of moving image shooting, the shot image is shot up and down. This is a phenomenon called camera shake.

  FIG. 7A is a side view showing an operation at the time of camera shake correction by the camera module 100, and FIG. 7B is a photographed image taken by the camera module 100 in FIG. 7A. It is a schematic diagram shown. As shown in FIG. 7A, when camera shake occurs, the OIS unit 3 shifts the image sensor unit 5 in the −X direction so that the center Oc of the subject O matches the optical axis s. Accordingly, as shown in FIG. 7B, the center OIc of the subject image OI and the center Ic of the photographed image can be matched, so that camera shake can be corrected.

  Here, the lens unit 11 included in the camera module 100 according to the present embodiment has an image height-optical distortion curve as shown in FIG. That is, it has an optical distortion characteristic in which the optical distortion gradually decreases in the vicinity of the maximum image height (± 100%) and the maximum image height.

  For this reason, as shown in FIG. 7 (b), in the image taken at the time of camera shake correction taken by the camera module 100, the image taken at the time of camera shake correction taken by the conventional camera module 200 shown in FIG. 9 (b). Compared to the above, distortion of the subject image OI is suppressed. This is because in the camera module 100, the amount of tilt at the time of camera shake correction is reduced compared to the conventional camera module 200.

  FIG. 8 is a graph showing the optical distortion of the lens unit 11 at the time of camera shake correction shown in FIG. As shown in FIG. 8, the image height-optical distortion curve at the time of camera shake correction is caused by the shift of the image sensor unit 5 by the OIS unit 3 in addition to the change amount of the optical distortion caused by the tilt of the camera module 100 with respect to the subject O. The amount of change in optical distortion is added.

  In the present embodiment, since the lens unit 11 has the image height-optical distortion polarity shown in FIG. 3, the amount of change in optical distortion caused by the tilt of the camera module 100 with respect to the subject O, and the image sensor unit 5 by the OIS unit 3. The amount of change in the optical distortion caused by this shift becomes the opposite polarity and can be canceled out. As a result, as shown in FIG. 8, the amount of tilt can be reduced, and distortion of the captured image at the time of camera shake correction can be suppressed.

[5] Summary As described above, the camera module 100 according to this embodiment includes the lens unit 11 including at least one optical lens 11a to 11c and the optical unit 1 including the lens barrel 12 that holds the lens unit 11. The relative positions of the image sensor unit 5 having the sensor chip 52 that converts the light incident through the lens unit 11 into an electrical signal and the optical unit 1 and the image sensor unit 5 according to the inclination of the apparatus main body. By shifting in parallel with the imaging surface of the sensor chip 52, the OIS unit 3 that corrects the deviation of the optical axis with respect to the sensor chip 52 and the image height-optical distortion curve of the lens unit 11 are positive in the intermediate image height region. The maximum value is gradually decreased from the maximum value toward the maximum image height (± 100%).

  According to the above configuration, the image height-optical distortion curve of the lens unit 11 has a positive maximum value in the intermediate image height region, and gradually decreases from the maximum value toward the maximum image height. The change amount of the optical distortion caused by the tilt of the camera module 100 with respect to the subject O and the change amount of the optical distortion caused by the shift of the sensor chip 52 by the OIS unit 3 have the same reverse polarity.

  For this reason, since the amount of change in optical distortion caused by the tilt of the camera module with respect to the subject O and the amount of change in optical distortion caused by the shift of the sensor chip 52 by the OIS unit 3 are canceled out, the amount of tilt during camera shake correction is reduced. Thus, distortion of the captured image can be suppressed.

  As described above, the camera module 100 according to the present embodiment does not include a special ISP (Image Signal Processor) as in the prior art, and optimizes the image height-optical distortion curve of the lens unit, thereby correcting camera shake. The distortion of the captured image can be suppressed.

  Therefore, according to the present embodiment, the camera module 100 that is small in size and can suppress distortion of a captured image during camera shake correction is realized at low cost.

  In the present embodiment, a configuration including a sensor shift type camera shake correction mechanism as the OIS unit 3 has been described, but the present invention is not limited to this. For example, instead of the sensor shift type optical camera shake correction mechanism, a lens shift type camera shake correction mechanism may be provided.

  In the present embodiment, an example of the image height-optical distortion curve of the lens unit 11 has been described with reference to FIG. However, in the image height-optical distortion curve of the lens unit 11, the amount of change in optical distortion caused by the tilt of the camera module 100 with respect to the subject O is opposite to the amount of change in optical distortion caused by the shift of the sensor chip 52 by the OIS unit 3. If it becomes polarity, it will not specifically limit.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments, respectively. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is particularly suitable for use in camera modules that are mounted on various electronic devices such as digital cameras, digital still cameras, mobile phones, personal digital assistants, personal computers, and other communication devices such as portable terminals. Can do.

1 Optical part (optical means)
2 Lens drive unit 3 OIS unit (camera shake correction means)
4 Imaging unit 5 Image sensor unit (sensor means)
6 Substrate 11 Lens portion 11a Optical lens 11b Optical lens 11c Optical lens 12 Lens barrel 52 Sensor chip (imaging device)
100 camera module s optical axis O subject Oc subject center Ic photographed image center OI subject image OIc subject image

In order to solve the above-described problem, a camera module according to the present invention is incident via an optical unit having a lens unit including at least one optical lens and a lens barrel that holds the lens unit, and the lens unit. Sensor means having an image sensor for converting the converted light into an electrical signal, and the relative position of the optical means and the sensor means is shifted in parallel to the imaging surface of the image sensor in accordance with the inclination of the apparatus body. Thus, in a camera module including a camera shake correction unit that corrects a deviation of the optical axis with respect to the imaging element, the image height-optical distortion curve of the lens unit has a positive maximum value in the intermediate image height region, and the maximum and gradually decreases from the maximum value toward the image height, the maximum image height and the optical distortion of the maximum image height near The amount of decrease is approximately the same as the amount of change in optical distortion caused by the inclination of the apparatus body and the amount of change in optical distortion caused by a relative position shift between the optical means and the sensor means by the camera shake correction means. It is characterized by being determined as follows.

As described above, according to the above-described invention, it is possible to suppress distortion of a captured image at the time of camera shake correction by optimizing the image height-optical distortion curve of the lens unit. the camera module capable of suppressing distortion of the captured image at the time of correction Ru can be realized at low cost.

According to the above invention, the amount of change in the optical distortion caused by the tilt of the camera module with respect to the subject and the optical distortion caused by the relative positional shift between the optical means and the sensor means by the camera shake correction means are comparable. Since it has a reverse polarity, it is offset. Note that the range in the vicinity of the maximum image height is appropriately determined based on the tilt of the camera module with respect to the subject and the amount of shift of the relative position between the optical means and the sensor means by the camera shake correction means.

Claims (7)

An optical means having a lens portion composed of at least one optical lens and a lens barrel for holding the lens portion;
Sensor means having an image sensor for converting light incident through the lens unit into an electrical signal;
Camera shake correction that corrects a deviation of the optical axis with respect to the image pickup device by shifting the relative position of the optical means and the sensor means in parallel with the image pickup surface of the image pickup device in accordance with the inclination of the apparatus body. Means,
In a camera module comprising
An image height-optical distortion curve of the lens portion has a positive maximum value in an intermediate image height region, and gradually decreases from the maximum value toward the maximum image height.   The amount of decrease in optical distortion near the maximum image height and in the vicinity of the maximum image height is the amount of change in optical distortion caused by the inclination of the apparatus body and the relative position between the optical means and the sensor means by the camera shake correction means. 2. The camera module according to claim 1, wherein the amount of change in optical distortion caused by the shift is determined to be approximately the same.   3. The camera module according to claim 2, wherein the amount of reduction is 0.1% or more and 0.5% or less per 1 image height.   The camera module according to claim 2, wherein the intermediate image height region is a region that is 30% or more and 60% or less with respect to the maximum image height.   5. The camera shake correction unit according to claim 1, wherein the camera shake correction unit is a lens shift type optical camera shake correction mechanism that corrects a deviation of an optical axis with respect to the imaging element by shifting the optical unit. Item 1. A camera module according to item 1.   5. The camera shake correction unit is a sensor shift type optical camera shake correction mechanism that corrects a deviation of an optical axis with respect to the image pickup device by shifting the sensor unit. Item 1. A camera module according to item 1. An imaging apparatus comprising the camera module according to claim 1.

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